1. Technical Field
This document discloses a wheel housing with an accumulator, and in particular, a wheel housing that uses coolant or oil to cool a brake assembly and an accumulator disposed in the wheel housing to alleviate pressure concerns of the coolant.
2. Description of the Related Art
Mobile machines are equipped with one or more brake systems to slow the machines in response to an operator input. Typical brake systems can include one or more dry brakes and/or one or more wet brakes associated with different axles and/or wheels of the machine. Wet brakes are similar in construction to dry brakes but include a coolant circuit that flows through the wet brake assembly to cool the assembly after generating substantial amounts of heat during use. While dry brakes are simple, inexpensive, and easy to service in comparison to wet brakes, dry brakes also wear faster and have lower braking capacities than wet brakes due to the extreme temperatures generated when dry brakes are applied.
Both wet and dry brakes generally include a stationary reaction plate, a slidable member in the form of a pressure plate or a service piston, and one or more friction plates sandwiched between the reaction plate and slidable member. The friction plates connect to and rotate with the associated axle or wheel. Non-rotating spacer or separator plates interleaved between the friction plates create a row of alternating friction and separator plates known as a disc stack. Both types of brakes also include a biasing mechanism, such as a spring or source of pressurized fluid, which urges the slidable member towards the reaction plate, thereby squeezing the disc stack therebetween. In this arrangement, the biasing element, via the slidable member, separator and reaction plates, generates and applies a pressure on or squeezes the rotating friction plates. The frictional contact between the slidable member and the friction, separator and reaction plates generates substantial amounts of heat, which is reduced by the coolant circuit of a wet brake.
Specifically, the disc stack of a wet brake is submerged in circulating coolant or oil that cools the disc stack during operation. Wet brakes cooled via circulating oil are also known as force-cooled wet brakes. The oil used to cool the plates of a wet brake is contained within a closed circuit. To keep the oil used to cool the disc stack from leaking out of the circuit, seals are used between the stationary axle housing and the rotating hub and/or between stationary components of the wet brake assembly and the rotating hub. These seals may be mechanical face seals, also known as duo cone seals.
Regardless of the type of seal used, premature failure of the seals can occur because of pressure spikes resulting from the volume of oil expelled from the disc stack as the friction and separator plates are squeezed together during braking events. These pressure spikes may exceed the working limit of the seals, which may lead to premature failure of the seals. US2013/200687 discloses a hydraulic braking system that includes a damper inside a separate hydraulic housing upstream of the wheels for relieving pressure spikes in the hydraulic braking system. The separate housing contains a bladder filled with magneto-rheological fluid and a magnetic coil wraps around the housing for controlling the action of the bladder. US2013/200687 does not address the issue of pressure spikes in the oil circuit used to cool the disc stack of a wet brake.
Accordingly, a means is needed for a reducing pressure spikes in the coolant or oil circuits of wet brake assemblies.